Laboratory calibration of «pharmaceutical» POCIS: kinetic accumulation and sampling rates of polar organic contaminants and evaluation of candidate performance reference compounds (PRCs)
Calibration en laboratoire du POCIS "pharmaceutique" : cinétiques d'accumulation et taux d'échantillonnage de contaminants organiques polaires et évaluation de composés de référence et de performance (PRC) potentiels
Résumé
POCIS (Polar Organic Chemical Integrative Sampler) is a new emerging tool for sampling polar organic micropollutants in water (Alvarez et al., 2004). It is still in development concerning its domain of validity (e.g. molecules sampled, type of water studied, optimal exposure duration) and its performances, including the definition of molecules sampling rates, repeatability, accuracy of the evaluation of time-weighted average (TWA) concentrations. Performance reference compounds (PRCs) enable to decrease the effect of variable environmental conditions, so they can be used to obtain more reliable TWA concentrations in situ. To our knowledge, for POCIS, only one PRC has been identified to date: deisopropylatrazine-d5, that has been used and proved efficient for polar herbicides monitoring in freshwater (Mazzella et al., 2007, 2010). In order to obtain in situ TWA contaminant concentrations, POCIS needs to be calibrated in laboratory for each molecule of interest. Our work was based on laboratory calibration of POCIS for 5 alkylphenols, 9 hormones, 11 pesticides, 27 pharmaceuticals, 3 phenols and 1 UV filter in a flow-through system. This system was composed of 2 aquaria (50 L) containing i) spiked tap water (circa 3 µg/L) and non-spiked POCIS for the determination of accumulation kinetics or ii) non-spiked tap water and spiked POCIS for the determination of desorption kinetics. In both experiments, water temperature, pH, conductivity and dissolved organic carbon were controlled. Agitation in the aquaria was ensured via a submerged pump. The resulting flow velocity was 10±5 cm/s and was directed perpendicularly towards POCIS surface. Triplicate POCIS were analyzed at 3, 7, 11, 14, 21 and 28 days. We will present various results depending of molecules such as the duration of linear accumulation phase and sampling rates, sampling repeatability and possible PRCs.